Rear portion of a helmet



FIG. 1 is a perspective view of a rear portion of a helmet as seen from the rear and upper left, showing my new design;

FIG. 2 is a left side elevational view thereof, the right side is a mirror image;

FIG. 3 is a top plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom plan view thereof.

The portion of the helmet shown in broken lines is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a rear portion of a helmet, as shown and described. 